JSON for Modern C++ 3.8.0

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basic_json
basic_json
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~basic_json
| ## ◆ to_msgpack() [1/3]
static std::vector<uint8_t> nlohmann::basic_json::to_msgpack | ( | const basic_json & | j | ) |
| inline static
Serializes a given JSON value j to a byte vector using the MessagePack serialization format. MessagePack is a binary serialization format which aims to be more compact than JSON itself, yet more efficient to parse. The library uses the following mapping from JSON values types to MessagePack types according to the MessagePack specification:
JSON value type | value/range | MessagePack type | first byte
--- | --- | --- | ---
null | `null` | nil | 0xC0
boolean | `true` | true | 0xC3
boolean | `false` | false | 0xC2
number_integer | -9223372036854775808..-2147483649 | int64 | 0xD3
number_integer | -2147483648..-32769 | int32 | 0xD2
number_integer | -32768..-129 | int16 | 0xD1
number_integer | -128..-33 | int8 | 0xD0
number_integer | -32..-1 | negative fixint | 0xE0..0xFF
number_integer | 0..127 | positive fixint | 0x00..0x7F
number_integer | 128..255 | uint 8 | 0xCC
number_integer | 256..65535 | uint 16 | 0xCD
number_integer | 65536..4294967295 | uint 32 | 0xCE
number_integer | 4294967296..18446744073709551615 | uint 64 | 0xCF
number_unsigned | 0..127 | positive fixint | 0x00..0x7F
number_unsigned | 128..255 | uint 8 | 0xCC
number_unsigned | 256..65535 | uint 16 | 0xCD
number_unsigned | 65536..4294967295 | uint 32 | 0xCE
number_unsigned | 4294967296..18446744073709551615 | uint 64 | 0xCF
number_float | any value | float 64 | 0xCB
string | length: 0..31 | fixstr | 0xA0..0xBF
string | length: 32..255 | str 8 | 0xD9
string | length: 256..65535 | str 16 | 0xDA
string | length: 65536..4294967295 | str 32 | 0xDB
array | size: 0..15 | fixarray | 0x90..0x9F
array | size: 16..65535 | array 16 | 0xDC
array | size: 65536..4294967295 | array 32 | 0xDD
object | size: 0..15 | fix map | 0x80..0x8F
object | size: 16..65535 | map 16 | 0xDE
object | size: 65536..4294967295 | map 32 | 0xDF
binary | size: 0..255 | bin 8 | 0xC4
binary | size: 256..65535 | bin 16 | 0xC5
binary | size: 65536..4294967295 | bin 32 | 0xC6
  Note The mapping is complete in the sense that any JSON value type can be converted to a MessagePack value. The following values can not be converted to a MessagePack value: strings with more than 4294967295 bytes byte strings with more than 4294967295 bytes arrays with more than 4294967295 elements objects with more than 4294967295 elements The following MessagePack types are not used in the conversion: float 32 (0xCA) Any MessagePack output created to_msgpack can be successfully parsed by from_msgpack. If NaN or Infinity are stored inside a JSON number, they are serialized properly. This behavior differs from the dump() function which serializes NaN or Infinity to `null`. Parameters
  [in] | j | JSON value to serialize
  Returns MessagePack serialization as byte vector Complexity Linear in the size of the JSON value j. Example The example shows the serialization of a JSON value to a byte vector in MessagePack format. 1 #include <iostream> 2 #include <iomanip> 3 #include <nlohmann/json.hpp> 4 5 using json = nlohmann::json; 6 7 int main() 8 { 9 // create a JSON value 10 json j = R"({"compact": true, "schema": 0})"_json; 11 12 // serialize it to MessagePack 13 std::vector<uint8_t> v = json::to_msgpack(j); 14 15 // print the vector content 16 for (auto& byte : v) 17 { 18 std::cout << "0x" << std::hex << std::setw(2) << std::setfill('0') << (int)byte << " "; 19 } 20 std::cout << std::endl; 21 } Output (play with this example online):
      0x82 0xa7 0x63 0x6f 0x6d 0x70 0x61 0x63 0x74 0xc3 0xa6 0x73 0x63 0x68 0x65 0x6d 0x61 0x00
  The example code above can be translated with
      g++ -std=c++11 -Isingle_include doc/examples/to_msgpack.cpp -o to_msgpack
See also http://msgpack.org from_msgpack for the analogous deserialization to_cbor(const basic_json& for the related CBOR format to_ubjson(const basic_json&, const bool, const bool) for the related UBJSON format Since version 2.0.9 Definition at line 22884 of file json.hpp.

nlohmann::basic_json::to_msgpack
static std::vector< uint8_t > to_msgpack(const basic_json &j)
create a MessagePack serialization of a given JSON value
Definition: json.hpp:22884
nlohmann::json
basic_json<> json
default JSON class
Definition: json.hpp:2774